Anchor for dental prostheses

ABSTRACT

An anchor comprising a tubular housing adapted to be threaded into a tapped opening in a simulated tooth forming a part of a dental prosthesis. An axially movable, spring biased plunger is mounted in the housing for movement into an extended position of use in the natural undercut area of a fixed tooth in a patient&#39;&#39;s mouth and into a retracted position within the housing. The plunger is provided with an annular shoulder engagable with an abutment shoulder in the housing for limited movement into the extended position and an inner end engagable with a plug mounted in the housing for limited movement into the retracted position.

United States Pamnt 1 Konig 51 Feb. 27, 1973 1 ANCHOR FOR DENTAL PROSTHESES [75] Inventor: KarlKonig,Hagen-Haspe, Germany [73] Assignee: Bohadan Melnyk, Buffalo, NY.

[22] Filed: May 14, 1971 [21] Appl. No.: 143,443

[30] Foreign Application Priority Data Sept. 29. 1970 Germany ..o 70 35 972.9

[52] US. Cl ..32/5 [51] int. Cl ..A6lc 13/22 [58] Field of Search ..32/5, 6,7

[56] References Cited UNITED STATES PATENTS 4/1968 Weissman ..32/5

Primary Examiner-Robert Peshock Attorney-Christel & Bean [5 7] ABSTRACT An anchor comprising a tubular housing adapted to be threaded into a tapped opening in a simulated tooth forming a part of a dental prosthesis. An axially movable, spring biased plunger is mounted in the housing for movement into an extended position of use in the natural undercut area of a fixed tooth in a patients mouth and into a retracted position within the housing. The plunger is provided with an annular shoulder engagable with an abutment shoulder in the housing for limited movement into the extended position and an inner end engagable with a plug mounted in the housing for limited movement into the retracted positron.

PATENTEDFEBZYW 3,717. 931

I NVEN TOR.

Kari 15 0")??? BY W L ATTORNEYS.

1 ANCHOR FOR DENTAL raos'russns BACKGROUND OF THE INVENTION This invention relates generally to an anchor device and, more particularly, to an anchor deviceespecially adapted for use in prostheticdentistry.

Various types of detachable anchors or retaining devices are incorporated in dental prosthesesfor affixing the latter to the natural teeth in an individuals mouth. conventionally, such anchors are in the form of wire-like clasps which engage and embrace the natural teeth to retain the prosthesis in place. Not only are such clasps unsightly and detract from the general appearance of an individuals mouth, but their frictional engagement with the natural teeth and abrading action thereagainst during removal and placement of the prosthesis results in wear of the natural teeth and possible damage thereto. Moreover, the retentive qualities of such clasp-like anchors are not completely satisfactory in that they often permit some displacement and/or torquing of the prosthesis relative to the natural teeth.

SUMMARY OF THE INVENTION The dental prosthesis anchor of the present invention, ashereinafter described, obviates the above disadvantages by providing a removable anchor adapted to be threadably received in a tapped opening in the dental prosthesis in such a manner as to be substantially concealed and which provides adequate retention while preserving the natural teeth associated therewith.

Generally speaking, the dental prosthesis anchor of the present invention comprises a housing adapted to be threaded in an opening of a simulated tooth forming a part of the dental prosthesis. An axially movable, spring biased plunger is mounted in the housing and has a portion projecting outwardly of the housing for engagement with the undercut area of an adjacent natural tooth in the patients mouth at each side of the prosthesis for securing the prosthesis in place. The plunger is provided with an annular shoulder and an inner abutment face for limited axial movement in opposite directions.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side'elevational view, partly in cross section, of an anchor constructed in accordance with one form of this invention;

FIG. 2 is an end elevational view of the anchor of FIG. 1; and

FIG. 3 is a side elevational view, partly in cross section, showing a dental prosthesis incorporating the anchor of this invention and positioned in a patients mouth.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT I Referring now in detail to the drawings, there is shown in FIG. 1 an anchor, constructed in accordance with this invention and generally designated 10, comprising a tubular housing 12 having an external threaded portion 14 and an internal bore 16 terminating in an end wall 18 having a central opening 19 therein. The transition between bore 16 and opening 19 defines an annular abutment shoulder 20 extending A diametrical slot 22 is provided in the outer face 24 d of housing 12 for receiving a suitable hand tool for inserting and removing anchor 10 into and from the dental prosthesis with which it is associated. The depth of slot 22 is less than the thickness of end wall 18 so as to space bore 16 from slot 22 and avoid the necessity of removing any burrs resulting from the milling of slot 22 during production.

A plunger 26 is mounted in the housing 12 and comprises an inner body portion 28 disposed in bore 16 and an outer body portion 30 projecting through opening 19 and outwardly from housing 12. The outer body portion 30 is provided with a rounded tip 32 adapted to engage the natural permanent teeth or fixed bridgework of the patients mouth. An annular central enlargement or shoulder 34 is provided on the plunger 26 between body portions 28 and 30. The shoulder 34 of plunger 26 is normally biased against abutment shoulder 20 by a helical compression spring 36 disposed in the bore 16 between the plunger shoulder 34 and a plug 38 press fited into the bore 16 of housing 12. The plug 38 is provided with an inner face 40 serving as a stop for limiting inward movement of plunger 26 in its retracted or depressed position.

The shoulder 34 of plunger 26 fits snugly within the bore 16 of housing 12 and the outer body portion 30 also fits snugly within the opening 19 so as to positively guide the plunger 26 is a straight axial direction thereby avoiding tilting of the plunger 26 and possible jamming thereof within the housing 12. Also, the spring 36 is coaxially aligned with the plunger 26 to further guide the latter axially in housing 12. Another factor precluding jamming of the plunger 26 within housing 12 is that the distance between the opposing faces of plunger 26 and plug 38 is approximately equal to the distance that the outer body portion 30 normally projects beyond the end of housing 12 so that plunger 26 can be retracted or depressed only to the position in which the tip 32 is disposed substantially flush with the outer front face 24 of housing 12. This inward limiting movement of plunger 26 prevents the tip 32 from being depressed into the housing and becoming lodged behind shoulder 20.

FIG. 3 illustrates a pair of anchors 10 of the present invention threaded into previously formed tapped openings 42 provided in artificial or simulated teeth 44 forming the end teeth of a dental prosthesis 46, commonly referred to as a partial denture. The prosthesis 46 is composed of a suitable plastic material having a base and opposite side portions 48 (only one of which is shown in FIG. 3) custom-fitted to the patients mouth and gum formation. Of course, any number of artificial teeth 44, simulating natural teeth, may be included in the prosthesis 46 with anchors 10 embedded in those teeth 44 adapted to be disposed adjacent the patients natural teeth 50. In the illustrative embodiment depicted in FIG. 3, it will be seen that two anchors 10 are utilized in the end teeth 44 of prosthesis 46 to hold the latter in place between spaced natural teeth 50.

In guiding the prosthesis 46 into position toward the natural gum formation, the tip 32 of plunger 26 engages against the outer portion of the adjacent natural tooth 50 and is depressed inwardly thereby within housing 12 allowing the prosthesis 46 to be finally positioned in place. Each plunger 26 is urged outwardly by spring 36 to dispose tip 32 in the natural undercut area along the inner portion of tooth 50 adjacent the gum line. Each anchor is adjusted within opening 42 to position plunger 26 in its extreme extended position, as limited by abutment shoulder 20, in such a manner as to preclude the exertion of any substantial pressure against the natural tooth 50. While plunger 26 serves as a detent retaining the prosthesis 46 in place, it remains in a passive condition in its extended position so as not to apply substantial pressure against the natural teeth. The prosthesis 46 is readily removed by merely grasping the side portions 48 and' pulling in a direction away from the natural gum formation.

The plunger 26 preferably is formed of nylon to prevent scratching or marring of the natural teeth when being inserted in and removed from the users mouth. In those instances where the prosthesis is placed adjacent dental crowns or fixed bridgework, plunger 26 may be formed of metal and inserted into a specially formed cavity in the adjacent crown to securely position the prosthesis in place.

The present invention thus provides a simple anchor incorporated in a dental prosthesis for securely retaining the latter in place in a patients mouth without any displacement or torquing of the prosthesis during normal usage. Because the anchor is substantially concealed within the body of an artificial tooth, the prosthesis creates a visual impression simulating natural teeth whichis attractive in appearance as compared to the unsightly clasps employed with conventional dental prostheses. Moreover, wear and/or fatique on the natural teeth is minimized, if not eliminated, thereby extending the useful life of the latter. It has been found that the anchors 10 of the present invention may be incorporated in existing partial dentures which have proven unsuccessful thereby salvaging an otherwise useless partial denture.

A preferred embodiment of this invention has been described and illustrated in detail but it is to be understood that modifications may be made without departing from the broad spirit and scope of this invention.

I claim:

1. An anchor for a dental prostheses comprising: a housing having an external threaded portion adapted to be threaded in a dental prostheses; said housing having an internal bore terminating in an end wall having a central opening defining an internal annular shoulder between said bore and said opening, a plunger mounted within said housing for axial movement relative thereto into an extended position and a retracted position, said plunger having an inner body portion within said housing and an outer body portion disposed in said opening, a spring biasing said plunger to said extended position whereby said outer body portion projects through said opening axially outwardly from said housing, said plunger having an annular shoulder between said inner and outer body portions engagable with said housing shoulder for limiting movement of said plunger in an outward direction to said extended position, a plug mounted within said bore at the end opposite said end wall, said plug having an inner abutment face limiting movement of said plunger in a reverse direction to said retracted position, the distance between the opposing faces of said plug and the inner end of said plunger in its extended position being approximately equal to the distance that said outer body portion projects beyond the end of said housing thereby preventing retraction of the outer end of said outer portion inwardly past said housing end; said plug having an annular recess for receiving one end of said spring for properly positioning said spring within said housing; said spring serving as a guide for said inner body portion of said plunger.

2. An anchor according to claim 1 wherein said end wall has an outer face provided with a diametrical slot for receiving a tool, said slot having a depth less than the thickness of said end wall.

3. An anchor according to claim 1 wherein said plunger is formed of nylon and said outer body portion terminates in a rounded tip formation.

4. An anchor according to claim 1 in combination with a dental prosthesis having a tapped opening, said anchor housing external threaded portion being releasably secured in said tapped opening.v

5, The combination according to claim 4 wherein said end wall has an outer face provided with a diametrical slot having a depth less than the thickness of said end wall.

6. The combination according to claim 4 wherein said plunger is formed of nylon and said outer body portion terminates in a rounded tip formation engagable with a fixed tooth in a patients mouth. 

1. An anchor for a dental prostheses comprising: a housing having an external threaded portion adapted to be threaded in a dental prostheses; said housing having an internal bore terminating in an end wall having a central opening defining an internal annular shoulder between said bore and said opening, a plunger mounted within said housing for axial movement relative thereto into an extended position and a retracted position, said plunger having an inner body portion within said housing and an outer body portion disposed in said opening, a spring biasing said plunger to said extended position whereby said outer body portion projects through said opening axially outwardly from said housing, said plunger having an annular shoulder between said inner and outer body portions engagable with said housing shoulder for limiting movement of said plunger in an outward direction to said extended position, a plug mounted within said bore at the end opposite said end wall, said plug having an inner abutment face limiting movement of said plunger in a reverse direction to said retracted position, the distance between the opposing faces of said plug and the inner end of said plunger in its extended position being approximately equal to the distance that said outer body portion projects beyond the end of said housing thereby preventing retraction of the outer end of said outer portion inwardly past said housing end; said plug having an annular recess for receiving one end of said spring for properly positioning said spring within said housing; said spring serving as a guide for said inner body portion of said plunger.
 2. An anchor according to claim 1 wherein said end wall has an outer face provided with a diametrical slot for receiving a tool, said slot having a depth less than the thickness of said end wall.
 3. An anchor according to claim 1 wherein said plunger is formed of nylon and said outer body portion terminates in a rounded tip formation.
 4. An anchor according to claim 1 in combination with a dental prosthesis having a tapped opening, said anchor housing external threaded portion being releasably secured in said tapped opening.
 5. The combination according to claim 4 wherein said end wall has an outer face provided with a diametrical slot having a depth less than the thickness of said end wall.
 6. The combination according to claim 4 wherein said plunger is formed of nylon and said outer body portion terminates in a rounded tip formation eNgagable with a fixed tooth in a patient''s mouth. 